I can think of 3 options for you, although only one will be stable for the long term:
Build a new linux heavy forwarder that meets the requirements. I know that might not be the preferred option, but this is the only one that will keep you on mainline support.
Clone the Splunk version of lea_loggrabber and try to compile on your existing platform: https://github.com/splunk/opsec_lea Once complete, move the newly compiled version into the TA's folder and restart the Splunk process. You'll need at least gcc and other developer tools installed to make this approach work.